Button cells conventionally comprise a housing consisting of two housing halves: what is termed a cell cup and what is termed a cell top. By definition, the cell cup has a positive polarity and the cell top has a negative polarity. These halves are conventionally often produced as stamped and drawn parts from nickel-plated deep-drawn sheet metal. The housing may contain a very wide variety of electrochemical systems, for example, zinc/MnO2, primary and secondary lithium-ion systems or secondary systems such as nickel/cadmium or nickel/metal hydride.
The liquid-tight closure of button cells is conventionally carried out by crimping the edge of the cell cup over the rim of the cell top using a plastic ring arranged between the cell cup and the cell top and is used simultaneously as a sealing element and for the electrical insulation of the cell cup and the cell top. Such button cells are described, for example, in DE 31 13 309 A1.
Particularly button cells which comprise a lithium-ion system often have a winding-shaped assembly of at least one band-shaped positive electrode, at least one band-shaped negative electrode and at least one band-shaped separator. In such button cells, the electrodes generally connect to the electrodes via metallic current output conductors, the current output conductors usually being welded onto the housing halves. However, the contact-connection of the housing halves often causes difficulties or is very complex. In a lithium-ion system (which generally supplies a voltage of 2.5 to 4.2 V), the condition of the housing often also plays a considerable role. Particularly on the cathode side, conventional steel housings often do not satisfy the requirements with respect to permanent electrochemical stability, particularly at points of contact with the current output conductors. As a consequence, corrosion and gassing phenomena can arise within the cell housing, and these can irreversibly damage the cell.
It could therefore be helpful to provide button cells which are better matched to the described requirements than conventional button cells.